I’m assuming that you’re learning more about API testing for self development. Even if you have more specific goals in mind, your starting approach seems solid to me. Starting being the best plan in my opinion.
I’m a fan of tools like postman that make it easier to get going without too much prerequisites. Skimming through the Postman Docs, they look like a solid starting point.
When you get the basics, I think its worth exploring more complicated topics e.g. authentication, using programming languages, etc.
There’s lots of stuff online. The restful booker platform is one thats used alot. Related topic that has lots of other useful advice and links.